1. Technical Field
The present invention relates to a radioisotope battery and a manufacturing method thereof, and more particularly, to a radioisotope battery having deposited radioisotope Ni-63 and to a method of manufacturing the same.
2. Description of the Related Art
Generally, a radioisotope is an element which is radioactive among isotopes of any element. Radioisotopes have different decay methods depending on the kinds thereof, and emit radiations having unique energy and are decayed into stable isotopes.
The decay methods include not only α, β−, β+ decay but also EC decay wherein an atomic nucleus captures K-orbital electrons. Most of the radioisotopes emit extra energy as alpha rays, beta rays or gamma rays and finally become stable isotopes. The amount of the radioisotope is represented by radioactive intensity, that is, the number of decay processes per unit time.
A conventional isotope battery using beta-rays is configured such that a Ni-63 foil or a sealed ray source as a beta-ray emitter is placed on a Si PN junction structure to thus absorb beta-rays, thereby generating current. When the semiconductor PN junction process and the fabrication of the beta-ray source are separately performed in this way, beta-rays may be emitted to the outside. To shield such rays, an additional shielding package has to be provided outside the isotope battery.
Upon manufacturing the isotope battery, because a series of processes, including performing a semiconductor process, manufacturing a beta-ray source, assembling a semiconductor-beta-ray source, forming a shielding structure, etc. are separately implemented, the fabrication of the isotope battery becomes complicated and difficult.
As a related technique, generation of current for a long period of time using radiation of an isotope is disclosed in Korean Patent No. 0935351 (entitled “A Method for Power Increase in a Nuclear-Cell and A High Efficiency Beta-Cell Using It”).
As disclosed in Korean Patent No. 0935351, in the method of increasing charge in the beta battery for irradiating beta-rays generated from a radioisotope onto a semiconductor to thus achieve charge generation, a plurality of PN junctions comprising a P-type impurity and an N-type impurity formed on a Si substrate is continuously arranged in a transverse direction so that the area of the depletion layer is distributed largely toward the inside from one or both sides of the Si substrate, and one-side ends of the same type of impurities are connected to thus form a comb structure. Furthermore, an insulating layer is formed over the entire upper surface of the PN junctions formed in a transverse direction, after which a layer of any one isotope selected from among 63Ni, 3H and He for generating radiation over the area corresponding to the PN junction region is formed thereon. As such, the sum of the depth of the PN junction and the thickness of the insulating layer is formed so as to correspond to the range of radiation emitted from the isotope layer, and thereby the radiation reaches the lower portion of the depletion layer of the PN junction diode formed in a transverse direction, ultimately increasing the amount of generated charge without a reduction in electric field ε.
As another related technology, a Schottky assembly is used as a current generation source in lieu of a PIN semiconductor, provided that the radioisotope layer is stacked on only either of the metal and the semiconductor, thereby preventing a short-circuit through the radioisotope layer in the current flow between the metal and the semiconductor, which is disclosed in Korean Patent No. 0934937 (entitled “Radioisotope Battery”).
The invention disclosed in Korean Patent No. 0934937 comprises an insulating substrate; a Schottky assembly comprising a deposited Schottky semiconductor layer and a deposited Schottky metal thin film layer; a deposited radioisotope layer; and electrode pads formed on portions of the Schottky semiconductor layer and the Schottky metal thin film layer.
However, Korean Patent Nos. 0935351 and 0934937 as above did not take into consideration the radioisotope Ni-62 to prevent human bodies from being exposed to radiation emitted from the radioisotope Ni-63.